/Engine/Source/Editor/BlueprintGraph/Public/BlueprintActionFilter.h
Certain actions are associated with specific member fields (a member function call, a variable get/set, etc.) This retrieves that member field if there is one (not all actions have an associated field).
The member field associated with the wrapped action (null if there isn't one).
[FFieldVariant](API\Runtime\CoreUObject\UObject\FFieldVariant) GetAssociatedMemberField()